Well you got there in the end Here are the figures from my "rigorous" testing:

(Power draw was measured at the wall for the entire system, not just the GPUs)

1) Heaven Benchmark, both cards at stock: 585W (peak)

2) Heaven Benchmark, both cards at SOC speed: 608W (peak)

3) Furmark Burn Test, both cards at stock: 610W (peak)

4) Furmark Burn Test, both cards at SOC speed: 661W (peak)

I was amazed to see such low figures given how much "power hog" propaganda there is about the GTX 480. Well this should dispel any myths...even with both GPUs overclocked significantly (and overvolted), the power draw at 99% load stayed well below 700W.

I'm currently installing the latest F@H client to see how it compares with Furmark.

So far, rollo is far closer to the real figure than anybody else. He is also correct that Heaven doesn't stress the GPUs as much as Furmark might (but I ran Furmark too... all will be revealed shortly).

I'll give you a clue and I still don't think anybody will get it right:

Peak power draw for the entire system whilst running Heaven was below 700 watts.